ML12318A128
| ML12318A128 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/29/2012 |
| From: | Price J Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 12-495 | |
| Download: ML12318A128 (16) | |
Text
Dmno uuConciuIc Millstone Power Station 7 Dominion Rope Ferry Road Waterford, CT 06385 OCT 29 2012 U.S. Nuclear Regulatory Commission Serial No.12-495 Attention: Document Control Desk NSS&L/MAE R0 Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2 REQUEST FOR A REVISION OF AN EXEMPTION FROM 10 CFR 50, APPENDIX R.
SECTION III.G., "FIRE PROTECTION OF SAFE SHUTDOWN CAPABILITY" By letter dated June 30, 2011, Dominion Nuclear Connecticut, Inc. (DNC) submitted a request for exemption from 10 CFR 50, Appendix R, Section Ill.G, "Fire Protection of Safe Shutdown Capability" for Millstone Power Station Unit 2 (MPS2). The proposed exemption request would allow the use of operator manual actions (OMAs) in lieu of the requirements of Paragraph III.G.2.
By letter dated January 13, 2012, the NRC requested additional information (RAI) regarding the MPS2 exemption request. By letter dated February 29, 2012, DNC provided a response to the requested additional information. By letter dated July 12, 2012, the NRC approved the exemption request.
Upon review of the approved exemption, the following was identified:
- Operator manual action (OMA) 1 was omitted from Fire Area R-9.
" OMA 9, OMA 11 and OMA 1 were omitted from Fire Area R-1 3.
" OMA 9 and OMA 1 were omitted from Fire Area R-14.
As discussed in a telephone call between the NRC and DNC on October 3, 2012, the part of the DNC response to RAI-02.1 related to loss of instrument air was meant to remove loss of Instrument Air (IA) as an initiator for OMA 1, OMA 9, OMA 10 and OMA 11 in Fire Areas R-9, R-10, R-13 and R-14. A loss of IA is not postulated in these fire areas. However, these OMAs are required for postulated fire cable damage and loss of power, as discussed in the responses to other RAIs issued in the January 13, 2012 letter.
Review of the approved exemption also identified one additional item which requires clarification. Consistent with the DNC letter dated June 30, 2011, Attachment 1, pages 8 and 12, other statements are needed to be added to section 3.11.1 of the approved
Serial No.12-495 Docket No. 50-336 Page 2 of 3 exemption to clarify the nature of the combustible loading in fire area R-14 (i.e., low combustible loading in the lower 6.9 and 4.16 kV switchgear room and moderate combustible loading in the East Cable Vault area versus low combustible loading in both areas).
Consistent with the suggested clarifications provided above, it is requested that the approved exemption be revised to consistently address the subject OMAs and fire loadings. Attachment 1 contains a summary of requested changes to the affected sections of the issued exemption. The summary specifically includes the identified OMAs to fire areas where cable damage or loss of power is postulated and clarification of the combustible loading in fire area R-14.
If you have any questions regarding this submittal, please contact Ms. Wanda Craft at (804) 273-4687.
Sincerely, J. AIl Price Vice President - Nuclear Engineering Commitments made in this letter: None Attachments:
- 1. Summary of Recommended Changes to the Affected Sections in the NRC Approved Exemption from Specific Requirements of 10 CFR 50, Appendix R, Section III.G.2.
Serial No.12-495 Docket No. 50-336 Page 3 of 3 cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C2A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Director Bureau of Air Management Monitoring and Radiation Division Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127
Serial No.12-495 Docket No. 50-336 ATTACHMENT I Summary of Recommended Changes to the Affected Sections in the NRC Approved Exemption from Specific Requirements of 10 CFR 50, Appendix R.
Section III.G.2 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2
Serial No.12-495 Docket No. 50-336 Attachment 1 page 1 of 12 Summary of Changes to the Affected Sections Changes are shown in red Table 1 Area of Area Name Actions OMA Fire Origin Open Valve 2-CH-508 to Obtain OMA Charging Pump Suction from Boric 4 Facility Z1 Direct Current Acid Storage Tank Fire Area Facility Dire Roo end Open Valve 2-CH-509 to Obtain Pump OMA R-9 Switchgear Room and Suction from Boric Acid Storage Tank 5 Open Valve 2-CH-192 to Establish OMA Charging Pump Suction from I Refueling Water Storage Tank Area of Area Name Actions OMA Fire Origin Operate Valve SV-4188 from Panel C-10 OMA 22 Operate Speed Control Circuit H-21 from OMA Panel C-10 to Control Turbine Driven 17 Auxiliary Feedwater Pump Speed Operate 2-FW-43B from Panel C-10 OMA-9 Operate 2-MS-190B from Panel C-10 to OMA Transition from Main Steam Safety 11 Valves Check Local Condensate Storage Tank OMA20 Level Indication at LIS-54 89 West (Facility Z1) Pull Control Power Fuses and Ensure OMA Fire Area R-1 3 480 VAC Swichgear Breaker A406 is Open 16 Room Close Breaker DV2021 at Panel DV20 OMA 24 Open Valve 2-CH-508 to Obtain Charging OMA 4 Pump Suction from Boric Acid Storage Tank Open Valve 2-CH-509 to Obtain Pump OMA 5 Suction from Boric Acid Storage Tank Operate Pump P18C from Panel C-10 OMA 21 Open Valve 2-CH-192 to Establish OMA I Charging Pump Suction from Refueling Water Storage Tank I I
Serial No.12-495 Docket No. 50-336 Attachment 1 page 2 of 12 Area of Area Name Actions OMA Fire Origin Operate 2-FW-43B from Panel C-10 OMA-9 Open Valve 2-CH-508 to Obtain OMA 4 Charging Pump Suction from Boric Acid Storage Tank Open Valve 2-CH-509 to Obtain Pump OMA 5 Suction from Boric Acid Storage Tank Pull Control Power Fuses and Ensure OMA 14 Breaker A410 is Open to Isolate Required Bus Facility Z1 Pull Control Power Fuses and Ensure OMA 13 Fire Area Lower 4.16kV Breaker A408 is Open to Isolate R-14 Switchgear Required Bus Rom Vant Pull Control Power Fuses and Ensure OMA 23 Cable Vault Breaker A401 is Closed to Power Bus from the Emergency Diesel Generator Pull Control Power Fuses and Ensure OMA 15 Breaker A411 is Open to Isolate Required Bus Close Breaker DV2021 at Panel DV20 OMA 24 Open Valve 2-CH-192 to Establish OMA 1 Charging Pump Suction from Refueling Water Storage Tank Page 17 characteristics, The licensee further stated that a failure of MCC B-41 B could also serve as an ignition source and that an MCC failure normally results in a high intensity fire that lasts for a short duration, which makes it unlikely that it will cause sustained combustion of IEEE 383 qualified cables despite the fact that the subject cable trays Iinches are located approximately 6-81-e CC. The smoke detection system, which consists of an ionization smoke detector located directly over MCC B61, will aid providing prompt Fire Brigade response.
Serial No.12-495 Docket No. 50-336 Attachment 1 page 3 of 12 page- 42 changes to fire area R-9 discussion; 3.7.4 OMAs Credited for a Fire in this Area In their letter dated February 29, 2012 the licensee deleted OMAs 1 and 11 from the exemption request for fire area R-9 since loss of IA is no longer postulated.
3.7.4.1 AFW and Charging System Flow 3.7.4.1.1 OMAs 1., 4 and 5, - Open Valve 2-CH-192. Open Valve 2-CH-508 and Open Valve 2-CH-509 The licensee stated that for a fire in fire area R-9, the Charging system has OMAs identified and that the BASTs gravity feed valves, 2-CH-508 (OMA 4) and 2-CH-509 (OMA 5), may fail as is (closed) due to a loss of power supply. The licensee also stated that an OMA is in place to locally open the valves as part of restoring the Charging system and that once these valves are opened, the CR can establish charging flow within 2-3 minutes. The licensee further stated that establishing charging pump suction from the BASTs and restoring charging is required within three hours of reactor shutdown/loss of charging and that Charging is reestablished within 24 minutes (21 minutes to open the BASTs valves and 3 minutes to establish charging flow in the CR) which provides a 156 minute margin. The licensee further stated that prior to BAST depletion, Operators switch over to the RWST. The licensee further stated that cables for 2-CH-192 do not pass through the fire area but the valve may fail closed if DV10 lost power and that an OMA would be required to open valve 2-CH-192 (OMA 1). OMA I establishes the RWST as the suction supply for the charging system. The BASTs have a minimum TRM
Serial No.12-495 Docket No. 50-336 Attachment 1 page 4 of 12 specified inventory to ensure 72 minutes of flow after charging is reestablished and OMA I can be completed in 32 minutes which results in 40 minutes of margin.
3.7.4.2 OMA Timing AFW flow is established from the CR within the required 45 minute time period. The OMA to establish Charging system flow from the BASTs can be completed in 24 minutes which provides a 156 minute margin since the required completion time is 180 minutes. The OMA to establish Charging system flow from the RWST prior to BAST depletion can be completed in 32 minutes which provides a 40 minute margin since the required completion time is 72 minutes.
Changes to fire area R-13, starting on page 49 3.10.4 OMAs Credited for a Fire in this Area In their letter dated February 29, 2012, the licensee stated that deleted OMA. 1, 0, and 11, from the o -ompti.n roquet for fire area R-13-sUtie loss of IA is no longer postulated.
3.10.4.1 AFW Flow 3.10.4.1 1 OMAs 9, 22 and 17 -Operate Feed Regulating Valve 2-FW-43B from the C10 panel, Operate Supply Valve SV-4188 from Panel C10 and Operate Turbine Driven AFW Pump Speed Control Circuit H-21 from Panel C10 The licensee stated that for a fire in the area, OMAs are required to provide decay heat removal and restore Charging system flow to the RCS and that establishing
Serial No.12-495 Docket No. 50-336 Attachment 1 page 5 of 12 AFW flow to the credited SG is required within 45 minutes. The licensee stated that for a fire in the area, the required AFW flow path utilizes the TDAFW pump and that due to fire induced cable damage, AFW turbine steam supply valve (SV-4188) (OMA 22), and TDAFW turbine speed control (H21) (OMA 17) may not be available from the CR. The licensee further stated that the cable damage can be isolated and the TDAFW pump can be operated from the Fire Shutdown Panel (C-10) located in fire area R-2 and that an OMA is necessary to isolate the damaged cables and operate the TDAFW turbine speed control to maintain level in the SG. The licensee stated that in the case of 2-FW-43B, cable damage could result in spurious operation and that isolation of the affected cables and control of the valve can be accomplished at the C-10 panel (OMA 9), and that control of SG water level can be maintained using the speed control function of the TDAFW pump. The licensee further stated that the timeframe to establish control of TDAFW at the C-10 panel is 45 minutes and that after Reactor Operator 1 (RO-1) has established control of TDAFW pump speed at the C-10 panel (8 minutes), it will take an additional 2 minutes to establish AFW flow which results in a total time to establish AFW flow of 10 minutes, leaving a 35 minute margin.
3.10.4.1.2 OMAs 11 and 20 - Operate Valve 2-MS-190B from panel C10, Obtain, CST Level at Local Level Indicating Switch LIS-5489A The licensee stated that valves 2-MS-190B and 2-FW-43B can be operated from the C10 panel and that the OMA for local or C-10 operation of 2-MS-1 90B (OMA
- 11) is not required until after AFW flow is established and that PEO-1 will remain with the ADV to modulate steam flow per direction from the CR. The licensee further
Serial No.12-495 Docket No. 50-336 Attachment 1 page 6 of 12 stated that the final decay heat removal function is to monitor CST level from either the C-10 panel (LT-5282) or locally at the CST (11S-5489) (OMA 20) and that checking the level is not a short-term requirement because there is sufficient inventory in the CST to provide over 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> of water flow to the AFW system. The licensee further stated that a spurious start of the TDAFW coupled with 2-FW-43B failing open should not result in a SG overfill and that the nominal water level in the SG is maintained between 60-75% as indicated on the Narrow Range (NR) level instruments (i.e., the normal operating band). The licensee further stated that from the top of the normal operating band, more than 8000 gallons of water can be added before reaching 100 percent on the NR level instruments and allotting 8 minutes to establish operations from the C-1 0 panel and assuming all the flow from the TDAFW is filling one SG, approximately 4800 gallons can be added before regaining level control. The licensee further stated that there is also an additional 14,000 gallons of margin available before the SG would overfill (i.e., from 100 percent NR to the Main Steam nozzle).
3.10.4.2 Charging System Flow 3.10.4.2.1 OMAs 1, 4. 5, 16, 21, and 24 - Open Valve 2-CH-192, Open Valve 2-CH-508, Open Valve 2-CH-509, Pull Control Power Fuses for Breaker A406 and Ensure Breaker is Open, Operate Pumr P 18C from Panel C 10. and Locally Close Breaker DV2021 The licensee stated that for a fire in the area, the Charging system has OMAs identified. The BASTs gravity feed valves, 2-CH-508 and 2-CH-509, may fail as is, (closed) due to cable damage and that OMAs are (OMA 4 and 5) in place to locally
Serial No.12-495 Docket No. 50-336 Attachment 1 page 7 of 12 open these valves as part of restoring the Charging system. The licensee further stated that cable damage due to fire may also cause a spurious start of the P18C Charging Pump and that cable damage may be mitigated by isolating and operating P18C (OMA 21) at the C-10 panel. The licensee further stated that RO-1 is at C-10 and must manipulate the controls for P18C and that establishing pump suction from the BASTs and operating P18C is required within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of reactor shutdown/loss of Charging. The licensee further stated that completing the OMAs to reestablish Charging would take 23 minutes leaving a margin of 157 minutes, which includes the parallel actions of PEO-2 establishing control of Bus 240 (by pulling control power fuses to circuit breaker A406 (OMA 16), ensuring A406 is open and closing breaker DV2021 (OMA 24) and PEO-3 (by manually aligning valves 2-CH-508 and 2-CH-509). The licensee further stated that after the BASTs have reached the 10 percent level, Operators switch Charging Pump suction over to the RWST and valve 2-CH-192 may fail closed, but it can be controlled from the CR for approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> until after the depletion of the "A" battery, due to a loss of power supply to the battery charger. The licensee further stated that cables for 2-CH-192 do not pass through the fire area but the valve fails closed when battery "A" is depleted, and that an OMA would be required to maintain open valve 2-CH-192 (OMA 1). OMA I establishes the RWST as the suction supply for the charging system.
Serial No.12-495 Docket No. 50-336 Attachment 1 page 8 of 12 R-14 Changes, starting on page 53 3.11 Fire Area R-14. Lower 6.9 and 4.16 kV Switchqear Room. East Cable Vault 3.11.1 Fire Prevention The licensee stated that the Lower 6.9 and 4.16 kV Switchgear Room areas have low combustible loading that predominantly consists of cable insulation and Thermo-Lag fire resistant wrap, and that potential ignition sources include electrical faults.
The licensee stated that the East Cable Vault area have moderate combustible loading that predominantly consists of cable insulation and Thermo-Lag fire resistant wrap, and that potential ignition sources include electrical faults.
Continuing on page 55 3.11.4 OMAs Credited for a Fire in this Area In their letter dated February 29,2012, the licensee deleted OMAe--19--and 11 from the exemption request for fire area R-14 since loss of IA is no longer postulated.
The licensee stated that during verification and validation of the AOPs, it was identified that for a fire in fire area R-14 an additional operator might be necessary to place the plant into hot standby. The staffing requirements for MPS2 were changed to add one licensed or non-licensed operator over the minimum technical specification (TS) requirement to be on duty each shift during Modes 1, 2, 3, or 4, with this operator being designated as the Appendix R operator and is not part of the credited five man Fire Brigade crew.
Serial No.12-495 Docket No. 50-336 Attachment 1 page 9 of 12 3.11.4.1 Charginq and AFW System Flow 3.11.4.1.1 OMAs 4 and 5 - Open Valve 2-CH-508 and Open Valve 2-CH-509 The licensee stated that the Charging system has OMAs identified in that the BASTs gravity feed valves, 2-CH-508 and 2-CH-509, may fail as is (closed) due to a loss of power supply and that OMAs are in place (OMA 4 for 2-CH-508 and OMA 5 for 2-CH-509) to locally open these valves as part of restoring the Charging system.
The licensee further stated that establishing Charging Pump suction from the BASTs is required within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of reactor shutdown/loss of Charging and that RO-1 and PEO-3 will perform their OMAs in parallel (see Section 3.11.4.1.2) to restore Charging. OMAs 4 and 5 are completed in 21 minutes.
3.11.4.1.2 OMAs 1. 13, 14, 15, 23, and 24 - Open Valve 2-CH-192, Pull Control Power Fuses for Breaker A408 and Ensure Breaker is Open, Pull Control Power Fuses for Breaker A41 0 and Ensure Breaker is Open, Pull Control Power Fuses for Breaker A411 and Ensure Breaker is Open, Pull Control Power Fuses for Breaker A401 and Ensure Breaker is Closed, and Locally Close Breaker OV2021 The licensee stated that as part of the restoration of Charging flow to the RCS, Bus 24D must be isolated from cross-ties to Bus 24B, Bus 24E and the RSST and that this is due to fire induced cable damage which may result in spurious operation/loss of control from the CR of breakers A401, A410, A408 and A411, The OMAs associated with these breakers are to pull the control power fuses and ensure that breakers A410 (OMA 14), A408 (OMA 13) and A411 (OMA 15) are open and that breaker A401 (OMA 23) is closed, The licensee also stated that once RO-1
Serial No.12-495 Docket No. 50-336 Attachment 1 page 10 of 12 completes the OMAs, PEO-1 will then reset and close breaker DV2021 (OMA 24).
OMAs 13, 14, 15, 23 and 24 are completed in 24 minutes, then it will take an additional 3 minutes for the CR to establish Charging flow for a total of 27 minutes which results in a 153 minute margin since the required completion time is 180 minutes. The licensee further stated that after the BASTs have reached the 10 percent level, Operators switch Charging Pump suction over to the RWST.
Cables for valve 2-CH-192 do not pass through the fire area but the valve fail close when battery "A" is depleted, approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, due to a loss of power supply to the battery charger. OMA would be required to maintain open valve 2-CH-192 (OMA 1). OMA I maintains the RWST as the suction supply for the charging system.
3.11.4.1.3 OMA 9-Operate Feed Regulating Valve 2-FW-43B from the C10 panel The licensee stated that for a fire in the area, OMA 9 is required to provide decay heat removal. Establishing AFW flow to the credited SG is required within 45 minutes. The licensee stated that for a fire in the area valve 2-FW-43B cable damage could result in the valve not operational from the CR and that isolation of the affected cables and control of the valve can be accomplished at the C-10 panel (OMA 9). The licensee further stated that the timeframe to establish control of AFW at the C-10 panel is 45 minutes and that after Reactor Operator 1 (RO-1) has established control of 2-FW-43B at the C-10 panel (4 minutes), it will take an additional 2 minutes to establish AFW flow which results in a total time to establish AFW flow of 6 minutes, leaving a 39 minute margin.
Serial No.12-495 Docket No. 50-336 Attachment 1 page 11 of 12 3.11.4.2 OMA Timing The OMAs to establish Charging system flow from the BASTs can be completed in 27 minutes which provides for a margin of 153 minutes since the required completion time is 180 minutes. The OMA to establish AFW flow can be completed in 6 minutes which provides a 39 minute margin since the required completion time is 45 minutes.
Changes to table 3:
Available Time to Fire Area of Activity OMAs Time Conduct Margin Fire Origin (min) OMAs (min)
(me) (min)
Fire Area R-9 Establish 4,5 180 24 156 (Facility Z1 DC Charging Switchgear Suction from Room and BAST Battery Room) Establish 1 72 32 40 Charging Suction from RWST
Serial No.12-495 Docket No. 50-336 Attachment 1 page 12 of 12 Available Time to Fire Area of Fire AAvime Conduct Margin Origin Activity OMAs Time OMAs (min)
(mi) (min)
Fire Area R-13 (West (Facility Z1) 480 VAC Switchgear Room)
Establish AFW Flow Establish 9, 17, 22 4, 5, 16, 45 180 10 23 35 157 I
Charging 20, 21, Suction from 24 BASTs Establish 1 72 32 40 Charging Suction from RWST Fire Area R-14 Establish 9 45 6 39 (Facility Z1 Lower AFW Flow 4.16kV Switchgear Establish 4, 5,13, 180 27 153 Room and Cable Charging 14,15, Vault) Suction from 23, 24 BASTs Establish 1 72 32 40 Charging Suction from RWST A